Particular embodiments generally relate to a dual output direct current (DC)-to-DC regulator.
Unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
A charge pump is a DC-to-DC converter that uses capacitors to create either a higher or lower voltage output. Charge pumps use switches to control different connections for the capacitors. For example, in a first phase, a flying capacitor is connected to a voltage supply to charge the flying capacitor. In a second phase, the flying capacitor is disconnected from the voltage supply and connected to a second capacitor at an output. Charge then flows from the flying capacitor to the second capacitor, which increases the voltage across the second capacitor. The above process between the first phase and the second phase continues at a predetermined frequency. The process regulates the output voltage across the second capacitor to maintain the output voltage a desired level.
The charge pump regulates the output voltage at a single output. However, if multiple outputs are required, then an additional flying capacitor, an additional output capacitor, and an additional set of switches are needed to regulate the second output. This may be an inefficient use of integrated circuit (IC) chip area.
A voltage regulator is provided and includes a first capacitance, a second capacitance, a third capacitance, first switches and second switches. The first capacitance includes a first terminal. The first terminal is connected to a first output of the voltage regulator. The first output is at a first output voltage. The second capacitance includes a first terminal. The first terminal of the second capacitance is connected to a second output of the voltage regulator. The second output is at a second output voltage. The third capacitance includes a first terminal and a second terminal. The first switches are configured to connect the first terminal of the third capacitance to a voltage supply, the first output, or the second output. The second switches are configured to connect the second terminal of the third capacitance to a first reference terminal, the first output, or the second output. The first switches and the second switches are controlled, based on the first output voltage and the second output voltage, to (i) adjust voltages across the first capacitance, the second capacitance, and the third capacitance, (ii) maintain the first output at a first predetermined voltage, and (iii) maintain the second output at a second predetermined voltage.
A method of operating a voltage regulator is provided. The voltage regulator includes a first capacitance, a second capacitance, and a third capacitance. The first capacitance includes a first terminal connected to a first output of the voltage regulator. The second capacitance includes a first terminal connected to a second output of the voltage regulator. The third capacitance includes a first terminal and a second terminal. The method includes: providing a first output voltage at the first output; providing a second output voltage at the second output; performing a first determination of whether to connect the first terminal of the third capacitance to a voltage supply, the first output, or the second output; and based on the first determination, connecting, via first switches, the first terminal of the third capacitance to the voltage supply, the first output, or the second output. The method further includes: performing a second determination of whether to connect the second terminal of the third capacitance to a first reference terminal, the first output, or the second output; based on the second determination, connecting, via second switches, the second terminal of the third capacitance to the first reference terminal, the first output, or the second output; and based on the first output voltage and the second output voltage, controlling the first switches and the second switches to (i) adjust voltages across the first capacitance, the second capacitance, and the third capacitance, (ii) maintain the first output at a first predetermined voltage, and (iii) maintain the second output at a second predetermined voltage.
In one embodiment, an apparatus includes a first switch coupled to a first voltage reference and a second switch coupled to a second voltage reference. A third switch is coupled to a first terminal of a first capacitor and a first terminal of a second capacitor. A fourth switch is coupled to a second terminal of the first capacitor and the first terminal of the second capacitor. A fifth switch is coupled to the second terminal of the first capacitor and a first terminal of a third capacitor. A sixth switch is coupled to the first terminal of the first capacitor and the first terminal of the third capacitor. The first switch, the second switch, the third switch, the fourth switch, the fifth switch, and the sixth switch are controlled to maintain a first voltage level at a first output and a second voltage level at a second output.
In one embodiment, the apparatus includes a seventh switch coupled to the first voltage reference and an eighth switch coupled to the second voltage reference. A ninth switch is coupled to a first terminal of a fifth capacitor and the first terminal of the second capacitor. A tenth switch is coupled to a second terminal of the fifth capacitor and the first terminal of the second capacitor. An eleventh switch is coupled to the second terminal of the fifth capacitor and the first terminal of the third capacitor. A twelfth switch is coupled to the first terminal of the fifth capacitor and the first terminal of the third capacitor.
In one embodiment, a system includes the first reference voltage; the second reference voltage; the first capacitor; the second capacitor; and the third capacitor.
In one embodiment, a method includes: coupling a first switch coupled to a first voltage reference; coupling a second switch coupled to a second voltage reference; coupling a third switch coupled to a first terminal of a first capacitor and a first terminal of a second capacitor; coupling a fourth switch coupled to a second terminal of the first capacitor and the first terminal of the second capacitor; coupling a fifth switch coupled to the second terminal of the first capacitor and a first terminal of a third capacitor; coupling a sixth switch coupled to the first terminal of the first capacitor and the first terminal of the third capacitor, and controlling the first switch, the second switch, the third switch, the fourth switch, the fifth switch, and the sixth switch to maintain a first voltage level at a first output and a second voltage level at a second output.
The following detailed description and accompanying drawings provide a more detailed understanding of the nature and advantages of the present invention.